Main Entry: ad·di·tion

Pronunciation: \ə-ˈdi-shən, a-\

Function: noun

Etymology: addicion Anglo-French, from Latin addition-, additio, from addere

Date: 14th century

1 : a part added (as to a building or residential section)
2 : the result of adding : increase
3 : the act or process of adding; especially : the operation of combining numbers so as to obtain an equivalent simple quantity
4 : direct chemical combination of substances into a single product

— in addition : ²besides, also

— in addition to : combined or associated with : ¹besides 2